JERUSALEM, Israel -- Bulgarian authorities have released a video believed to show the person responsible for Wednesday's bus attack that killed five Israelis.

The suspect is dressed as a tourist, wandering in and out of the bus terminal with a large pack on his back. A hat and dark glasses cover the man's face.

Investigators said the suspect was also carrying a fake U.S. driver's license.

The late afternoon blast ripped through a bus full of Israeli tourists at the airport in the Black Sea resort of Burgas.

Prime Minister Benjamin Netanyahu and other Israeli officials quickly blamed Iran and its proxy Hezbollah. Following the attack, Israel warned of a forceful response against Iranian terrorism

"We see this clearly in a clear pattern of behavior by the Iranian regime," Mark Regev, spokesman for Prime Minister Benjamin Netanyahu, told CBN News. "Over the last months, we've had Iranian-sponsored attacks on Israeli targets in Thailand, in India, [and] in Georgia."

Israel dispatched investigators and medical crews to Bulgaria to help the investigation, treat the wounded, and recover bodies.

Regev said Israel would take a tough stand.

"We will do what needs to be done to protect our people and to bring the perpetrators of this terrible atrocity to justice," Regev said.

But Jerusalem Post military analyst Yaakov Katz said it's not that easy.

"The dilemma here is how to respond, and I think that when it comes to a response, Israel's going to need to be very careful because it will need to calculate whether it wants to be drawn into a larger conflict with Hezbollah or Iran," Katz said.

On the same day as the bomb blast in Bulgaria, a massive explosion in Damascus killed three top Syrian officials. Although the two attacks apparently are unrelated, both have enormous implications for Israel.

"We follow matters in Syria very closely," Regev said. "Obviously for most of the world what they see in Syria is a humanitarian crisis -- a government butchering its own people. For Israel, Syria is just over the frontier. And we have very concrete and immediate concerns."

Those concerns include what will happen to Syria's stockpile of chemical weapons.

"Israel is facing a huge strategic predicament right now with what's happening in Syria. The possibility that chemical weapons will begin to proliferate or spread throughout the region is something that I don't think Israel will be able to tolerate or stand by as it happens," Katz said.

"And I think that Israel might be forced or feel pressed to take action -- to take out those facilities where Syria's chemical weapons are being stored," he said.

Katz said it's clear Assad is losing control. The question for Israel and the rest of the region is who will be in charge of his massive supply of weapons if or when he falls.